Yes the old measurement was hub to hub.
I talked to Bob some today and expressed our concerns with the new map and the mention of the 72" width restriction on it. He told me today that they were considering the 72" measurement as outside of tire to outside of tire.

It doesn't matter what they "consider" it to be they wrote "Hub". If they wish to enforce something different then they need to update the regs. The shade of gray is should it be selectable hub which would be the wider point or wheel hub? Neither of which is a tire by any standards.